Power equalizer for power presses



' 1,633 66 June 21,1921. J NELSON ,2

POWER EQUALIZER FOR POWER PRESSES Filed June 1 1925 2 Sheets-Sheet 1- limnzan j/ziz #25500,

June 21, 1927. 1,633,266

- .LNELSON POWER EQilALIZ-ER FOR POWER I RESSES Filed June 1926 2 Shee'ts-Sheet 2 a ("-2 I I 2 Q o m i lhIZ Z ZfOr,

JZ 72J1 JVQLS 0n,

Patented June 21, 1927.

UNETED STATES JOHN NELSON, OF CHICAGO, ILLINOIS.

POWER EQUALIZER FOR- POWER I PRESSES.

This invention relates to power die presses. and more particuiarly to means for equalizing the power applied to the ram thereof, and thereby minimizing the shocks,

strains and stresses to which power presses are subject. As is well known, during the first half of the down stroke of the ram, in many instances no work is done and that all of the work is done during the last cart or last half of the down stroke. The result is that during the last half of the working stroke the speed of the drive shaft tends to slow up somewhat, but as soon as the work has been done and the ram commences its upward stroke there is a sudden upward jerk, which causes the crank shaft to speed up again. All of this causes a very uneven and irregular movement of the crank shaftand causes great strains and stresses thereon, its bearings and other parts of the press. Une object of the present invention is to obtain an even and regular motion for the crank shaft. Another object is to store up cnu'gy during the first half or idle motion of the down stroke of the ram and to utilize stored up energy during the working portion of the down stroke, to store up energy durin the first half of the up stroke of the ram thereby, resisting the usual upward jerk on the ram at the commencement of the up stroke, and thereafter utilize stored up energy, as an auxiliary power, in lifting the ram during the last half of its up stroke. Another object is to provide fluid pressure means for accomplishing the above mentioned results. Another object to provide varible fluid pressure means for accomplish ing said results. 1

The invention consists, therefore, in pressure means interposed between some sta tionary object and the ram, and connected to the ram in such manner that the pressure is utilized to exert a retarding action on he ram during the first part of the down stroke and to exert pressure on the ram during the remaining portion of its working stroke; to yieldingly resist sudden upward movement of the ram after it has completed its working stroke, and to aid in lifting the ram during the latter part of its up stroke. It further consists in fluid pressure means and connections between the fluid pressure means and ram for equalizing the powerapplied to the ram during the various portlons of its idle and working strokes. It further consists 1n the provision of variable pressure Application filed June 14, 1926. Serial No. 115,784;

means for equalizing thepower applied to the ram. It further consists of the several novelfeatures of construction, arrangement and combination of parts hereinafter fully set forth and particularly pointed out in the claims.

The invention is clearly illustrated in the drawings accompanying the specificatiomin which: 7

Fig. 1 is a front elevation of a power press equipped with equalizing means embodying a simple form of the present invention, certain parts being broken out to illustrateparts that would otherwise be hidden from view; Fig. 2 is a view, partly in side elevation and partly in vertical cross section, the

line being indicated at'2-2 in Fig. 1; Fig. 3 is a plan of the press frame and certain pressure cylinders and associated members of the power equalizing mechanism; Fig. 4c is a front elevation of the pressure cylinders and associated members of the power equalizing mechanism seen in Fig. 1 and :-;iio'\vi.ng the operating parts in a position different from that seen in Fig. 1, and Fig. 5 is a front elevation of a slightly modified form of the invention.

Referring to said drawings and first to Figs. 1 to 4, inclusive, the reference characters 10, 10, designate the upright frame members of a power press 11 of conventional form. As is customary, the press contains stationary, bolster 153 which supports the female die a, and a v rt-ically movable ram 13 guided on the uprights l0 and connected to the crank or cranks 14 of the crank shaft 15 by connectingrods 16. The male die 5, is mounted on the ram '13 as usual. As the parts just described are common and well known it is thought unnecessary to describe them in greater detail.

"In accordance with the present invention, I provide pressure means between some stationary object, as for instance, the press body itself, and the ram 13, which pressure means operates to retard the first portion of the down or working stroke of the ram, and to act an auxiliary to the power (which drives the crank shaft), during the operative or working portion of the down stroke, said pressure means acting also to yieldingly resist or retard the initial up stroke of the ram and to aid or act as an auxiliary power in lifting the ram during the last half or final movement towards the upper end its up stroke. a

In the form of the invention illustrated in Figs. 1 to l, pressure or compressed air cylinders 17, are provided which are shown as supported upon the cross member 18 ot the press frame by brackets 19 bolted or otherwise secured to the pressure cylinders and press frame. Said pressure or con'ipressed air cylinders are shown as secured to and supported by the press frame for the purpose of illustration only, as it is quite evident that they may be supported upon any adjacent support. In the form of the invention shown, tour compressed air cylinders 17 are illustrated, although this number isuot material to the invention broadly considered as any desired. number of cylinders may be employed, and said cylinders are shown as arranged in pairs, there being one pair on each side of the press frame and the two cylinders of each pair being in axial alinement with each other and spaced apart a slight distance. Within each cylinder is a piston or plunger 20, which is connected to the ram 13 by power transmitting elements, here shown as comprising a stem 21, links 22 and an operating rod or strut 23. Although the form of connection between the links and the piston stems is immaterial, I have shown heads 24 in the compression cylinders and secured to the stems, said heads being formed with ears to which the links are pivotedly connected by pins or bolts 25. The links 22 are pivotedly connected together and to the bar or strut 23 by pins or bolts 26 and the other end of each bar or strut .43 is connected to the ram 13, as tor instance by a bolt 27. The parts are so proportioned and arranged and when the ram is at the top of its up stroke, the pivotal connection between the links and bar or strut, is located above the axis of the compressed air cylinders, and when the ram is at the bottom of its stroke, said pivotal connection between the links and bar or strut, will occupy a position on the other side of the axis oi the cylinders. The space 28 between each plunger 20 and the head 29 of each cylinder 17 is the pressure or compressed air space of the cylinder, and in the operation of the mechanism each piston 20 operates against the fluid pressure contained in said space.

Fluid under pressure as for instance compressed air, is supplied to the compressed air cylinders 17, as for instance from a com,- pressed air tank 2-30, there being a pipe 81 leading from said compressed air tank and having branches 32 leading to and discharging into the compressed air spaces 28 of the cylinders 17. The pipe 31 may have a valve 33 thereon, whereby the pressure may be shut ofi from the cylinders, and drain cocks 34 may be provided on the cylinders 17 for draining them of the air and any Water that might collect therein.

The fluid under pressure may be supplied to the tank 30 by a suitable pump (not shown) connected thereto by a pipe in which is interposed a pressure regulating valve 36 which may be set to maintain the desired pressure in the tank 30 and pressure chambers 28 ot' the cylinders 17, A pressure gauge 37 on the pipe 35 indicates at all times the pressure in the system.

Inasmuch as it may be found advantageous to vary the pressure exerted on the ram by the power equalizing means forming the subject matter of this specification, l have provided means tor accomplishing this result, which as shown comprises means for increasing and decreasing the volume ot compressed fluid behind the pistons 20. As shown the volume oil the compressed air tank 30 may be varied, and this may be accomplished by making one of its heads, 38, adjustable on the tank. The head 38 is shown as having a threaded connection with the tank body, whereby by screwing up the head 38 the cubic contents of the tank is decreased and by screwing back the head the cubic contents is increased. he result is that when the volume of compressed air behind the pistons 20 is decreased, the pressure is correspondingly increased, temporarily, each time the pistons are forced back against the compressed air, and this increased pressure is made available after the links 22 of the power transmitting elements have passed the dead center or axis or the cylinders. When the volume of compressed air behind the cylinders is increased, the added pressure caused by the backward movement of the pistons against it, is not til) so great and in fact may be made practically negligible.

In the operation of the apparatus thus far described and starting with the ram at the top of its stroke, during the lirst hall oi its down stroke, the bars or struts. 23 are drawn down, the links 22 straightened out and the pistons forced back against the pressure with cylinders, consequently any acceleration of the speed of the crank shaft is resisted by the pressure action on the pistons. As soon as the pivotal connection between the links of each pair and the bar 23 pass the dead center line, the pressure in the cylinders, acting on the pistons, tends to force the latter forward, thereby, moving the pivotal connection between the links and bar 23' means embodying the present invention, is the positive braking action on the crank shaft at the top of the stroke of the crank. With the ordinary clutch and brake mechanism there is a possibility that the crank will pass beyond thetop of the stroke, there by bringing the ram down unexpectedly and causing serious injury. In the present means, since the downward movement of the crank is resisted-by the compressed air acting on the pistons of the power equalizing means, the apparatus acts as a positive stop for the crank shaft at the top or" the stroke.

In Fig. 5 a single pressure cylinder 17 a is shown, in which are two oppositely moving pistons 20", each connected to a link 22. The compressed air pipe 31 opens to a pressure chamber 28 located between the pistons. The cylinder and links are connected to two relatively movable members 10, 23, where by when the movable member is moved relative to the stationary one, from one extreme position to another extreme position the pistons are moved toward each other and against the pressure in the pressure chamber of the cylinder, thereby resisting the movement of the movable member during the first half of its movement from one extreme position to another, and as soon as the pivotal connection of the links pass the axis of the cylinder the pressure within the cylinder acts on the pistons and facilitates movement of the movable member in the last half of its movement toward said extreme position. The stationary member 10 may represent the press body and the movable members 23? two bars or struts that connect with the ram, or the members 23 may represent stationary members of the press frame and-1O a bar or strut connected with the ram. From this it is apparent that the pressure cylinders may be stationary or movable, and that the links may be connected to the ram or to a stationary object, such as the press body. Moreore-r in place of the links other equivalent means'may be interposed between the pistons and the relatively movable element for actuating the pistons. The pistons may be stationary and the cylinders may move on the pistons.

lilore or less variation of the exact details of construction is possible without departing from the spirit of this invention I desire, therefore, not to limit myself to the exact form of the construction shown and described, butintend, in the following claims, to point out all of the invention disclosed herein.

I claim as new, and desire to secure by Letters Patent:

1. The combination with a stationary press member and a movable press member which is movable between two extreme positions, of fluid pressure means mounted on one of said members, and power transmitting means for transmitting pressure from said fluid pressure means to the movable press memher, and including a IIlLlllLlrClllGCUOIlZll torce transmitting member connected to the other member of the press and operating it to in.- crease the pressure of said pressure means during the lirst portion of the movement of the movable press member from extreme position to another, and operating during remainder oi said movement of the movable press member, to transmit pressure from said pressuremeans to said movable press member.

2. The combination with a stationary press member and a movable press member which is movable between two extreme posit-ions, of variable fluid pressure means mounted on one of said members, and power transmitting means for transmitting pressure from said. variable fluid pressure means to the movable press member, and including a multi-directional force transmitting member mounted on the other member of the press and'operating to increase the pressure of said variable lluid pressure means during the first portion of the movement of the movable press member from extreme position to another, and operating during remainder of said movement otthe movable press memher, to transmit pressure from said variable fluid pressure meansto said movable press member.

3. Power equalizing means for the ram of power presses, comprising pressure means and power transmitting means, one being connected to a stationary support and the other connected to the movable ram, the ramv being movable between two extreme positions, said power transmltting means including a n'iulti-directional force transmitting member, operating to increase the pressure of said pressure n'ieansduring the first portion of the movement of said ram from one extreme position to another, and operating during the remainder of said movement of the ram, to transmit pressure from said pressure means to the ram.

4. Power equalizing means for the ram of power presses, comprising fluid pressure means and power transmitting means, one being connected to a stationary support and the other connected to the movable ram, the ram being movable between two extreme positions, said power transmitting means including a multi-directional force transmitting member, operating to increase the pres sure of said fluid pressure means during the first portion of the movement of said ram from one extreme position to another, and operating during the remainder of said movement of the ram, to transmit pressure from said fluid pressure means to the ram.

5. The combination with a stationary press member and a movable press member which is movable between two extreme poill)- sitions, of variable fluid pressure means mounted on. one of said members, and power transmitting means for transmitting pressure from said variable fluid pressure means to the movable member of the press, and including a n'iulti-directional force transmitting member connected to the other member of the press and operating to increase the pressure of said variable fluid pressure means during the first portion of the movement of the movable press member from extreme position to another, and operating during remainder of said movement of the movable press member to transmit pressure from said variable fluid pressure means to said movable press member.

6. Power equalizing means for the ram of power presses, comprising a fluid pressure cylinder, a piston therein, a link connected to said piston, and a connecting member connected to said link, the pivotal connection between the link and connecting member moving in a line at right angles to the axis of the pressure cylinder the cylinder being connected to one of the relatively movable elements of the press and the connecting member being connected to the other member of the press.

7. Power equalizing means for the ram of power presses, comprising in combination, a pair of spaced co-aXial pressure cylinders, mounted on the body of the press, a piston in each cylinder, a link connected to each piston, an operating strut between the links and ram of the press and having a pivotal connection with said links, said pivotal connection between the links and operating strut having right line movements in a direction at the right angles to said cylinders.

8. Power equalizing means for the ram of power presses, comprising in combination, a pair of oppositely disposed co-axial compressed air cylinders, pistons, one in each cylinder, a pair of toggle links, one connected to each piston, and a connecting bar connecting said toggle links with the ram of the press.

9. Power equalizing means for the rai of power presses, comprising in combination, a pair of spaced co-aXial compressed air cylinders, a compressed air tank connected to said cylinders, means for varying the capacity of said tank, pistons, one in each cylinder, a pair of toggle links, one connected to each piston, and a connecting bar connecting said toggle links to the ram of the press.

10. Power equalizing means for the ram of power presses, comprising in combination a pair of spaced co-axial compressed air cylinders, pistons, one in each cylinder, a compressed air tank connected to said cylinders, means for varying the volume of compressed air behind said pistons, a pair of toggle links, one link being connected to each piston and a connecting member connecting said toggle links to the ram of the press.

11. The combination with a die press ram and crank shaft for actuating the same, of fluid pressure power equalizing means, including a fluid pressure cylinder and piston therein, moving against the pressure therein during the first part of the down stroke of the ram, and a link connection between said power equalizing means and ram arranged in a direction transverse to the direction of movement of the ram and operating .to resist initial downward movement of said ram.

12. The combination with a die press ram and crank shaft for actuating the same, of a fluid pressure cylinder and piston therein, working against the pressure in the cylinder, a swinging link arranged in a direction transverse to the movement of the ram and connected to said piston and to the ram and moving with the ram, at the commencement of the downward stroke, in a direction to further compress the fluid in the cylinder.

JOHN NELSON. 

